Seismic prospecting apparatus



July 3l, 1956 E, T. Howes ETAI- SEISMIC PROSPECTING APPARATUS 2 Sheets-Sheet 1 Filed July 3, 1955 Qs Si 556A@ 7: Howes, WAL/AM E H0 INVENTORS.

Arrone/Vey.

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2,757,355 Patented July 31, 1956 2,751,355 sEIsMIC PROSPECTING ArPARATUs Edgar T. Howes, Pasadena, and William F. Hoy, Altadena, Calif., assignors, by mesne assignments, to United Geophysical Corporation, Pasadena, Calif., a corporation of California Application July 3, 1953, Serial N o. 366,030 21 Claims. (Cl. 340-7) This invention relates to geophysical prospecting apparatus, and more particularly to improvements in apparatus for reflection seismic surveying.

Two methods of reflection seismic surveying are commonly employed, one of these methods being known as correlation shooting and the other being known as continuous profiling.

In reflection seismic surveying, seismic waves are generated by detonating an explosive charge at a shotpoint adjacent the surface of the earth, usually below the weathered layer. The seismic waves so generated travel downwardly through successive subterranean strata and small amounts of the energy in the seismic waves are reflected upwardly by the successive strata. Reflected waves returning to the surface of the earth from the various strata are detected `at various seismic wave receiving stations located at the surface of the earth and records are made of the returned waves. The time required for the waves to travel from the generating station to the successive strata `and thence by reilection to the receiving stations is determined from the records, and these times are employed in the determination of the depth, the strike and the dip of the various reflecting strata. In correlation shooting the similarity of waves in different records is employed to recognize reflections from different widely spaced-apart portions of various strata.

In continuous proliling, a large number of receiving stations are employed and they are so arranged relative to the generating stations that waves are reflected from sub-surface strata from a series of relatively closely spaced points, and the time of travel of waves from closely spaced points that are recorded on different records is very nearly the same. Continuous proling methods are described and claimed in Patent No. 2,329,721 issued to Herbert Hoover, Jr., et al., and Patent No. 2,259,478 issued to Charles Gill Morgan.

number of spreads of receiving stations, but changing either the generating station or the spread of receiving stations or both between successive records. In any event, in continuous profiling, seismic waves are reflected from successive contiguous portions of the sub-surface strata which waves are reilected from a particular generating point and received simultaneously at a particular spread in the area surveyed. This information is then employed as a guide in locating wells in an area under investigation or undergoing development.

In practice, it is desirable to record high frequency wave to travel from a generating point to various reflecting strata and thence to a reception point. Accuracy in such measurements, in turn, assists the making of accurate surveys of subterranean formations.

In both continuous profiling and in correlation shooting, the waves are received by seismometers located at reception points at or adjacent the surface of the earth. Frequently, seismometers are placed directly upon the surface of the earth. Sometimes they are buried a short distance beneath the surface. In either event, the adjacent part of the earth constitutes an elastic medium which acts as a resilient member supporting the mass of the seismometer. Such a system has a resonance characdensity of the earth material,

quently, the resonant frequency lies in the range of between about and yabout 200 C. P. S. (cycles per second). Since reflected seismic waves frequently contain substantial energy in that frequency range, the apparent time of reception of the waves varies from one seismometer to another because of the fact that the various resonant systems formed between the various seismometers and the ground have different resonant frequencies. Errors also arise because the damping characteristics of the resonant systems vary from one receiving station to another. For this reason, seismic in the timing of the recording of the waves.

an area to be explored by the methods of reflection seismic surveying has a weathered layer overlying a series of strata. Such a weathered layer is characterized by a relatively low seismic wave velocity in the range of about 500 feet per second to about 2,000 feet per second. The weathered layer also varies in thickness from one such point to another. Furthermore, the velocity varies from point to point horizontally in the area under investigation. As is well known, account is taken of such variations by weathering correction techniques.

Generally, beneath the weathered layer, there is a series of strata that are characterized by relatively high seismic wave velocities of 5,00] feet per second and higher. This velocity generally increases with depth. The velocity at any depth or in any particular stratum is relatively uniform from point to point throughout the area, or at least if it does vary, it varies to a smaller degree and in a relatively uniform manner compared with the corresponding variations in velocity in the weathered layer.

According to the invention described and claimed in copending patent application Serial No. 319,969, led 1952, by Raymond A. Peterson, reflected t 3 .A Best rhode "of pr 4ticing that invention now contemplated, a substantial number, if not all, of 'the receiving stations are located at a depth of about a Wavelength or more ben eath the weathered layer. Furthermore, in the best tiroide of p'racticiii`g that "invention, th receivers located at the receiving stationsare in the form of li'ydrphones, wijnen sie' immersed in liquid in a receiver nale. t invention is 'concerned particularly Jwith the apparatus employed in 'the practice of "th ven ln of said 'ee'piidin'g application, sid apparatus iniudmg 'a ity of hydrop bries arranged atst'a'tionsin predened spaced 'relation along a cable which lowered the receiver hole containing liquid. 'O'i objo't f 'the present invention yis to pfvidefa hydrophone structure which is highly ctic'al and lciiit iii,`se, f

irivetioh, 'iniiltiple conductor cable extends downwardly into the n eive' hole with lts individual Conductors c'oiine'cied to 'the 'respective prearnplii'iers lof the rsuccessive l diphones of the series.

h'e'r object of the invention is lto provide a yseries ot' y nes in Iwhich a r'n'ul'tiple conductor cable 4is composed 'of "a irnber of sections, each section having its 'ds V"ex' ndniginto successive casings of the series,

' ted between adjacent hydrophones.

,eeft iste provide a hydrophose n wnfeh the eiids 'thefc'onducto'r cable sections entend into the cslateral ings formed therein, the cable ssd land thus free from forces which hi fr'o'rr'l 'the hydropho'n'es, lthe 'latter tlin the receiver hole solely th Another object is 'to vrprov-ide 'a Vrnultipl'e hy." system iArye/friert the several edudueforsf th cable sections 'ar'e connected to lrrniltiple 'terminal p ugA at t e ends ofthe sections, the plugs being iulll enclosed withi1`1` `the ends 'of the 'hydrophone 'casings A r'efat'el Objectis to lprovide': connecting rn'ean's for retaining t e te' inalplugs within the casings, said means embodying compres'sihle se'aling 'elerrents by which the plugs are effectively sealed froin `the'eit'eri'o'r of "the cas-ings to lvi/iihstand 1the high hydrostatic 'pressure Aeiiis'tinfg' within 'the receiver hole. According to the invention, one of v"the sealing elements is vulcanized to and around Vthe sheath er sach eaauefor cable season 'so as te prevent 'lek'age along said sheath, the vulcanized element thus being in trie nature 'o'f'a cylindrical enlargement of the cable section, the element having a frustoaconical end .providing a tapered inner surface of a collar which is forced "thereagainst by means of a nut-like element screwed into the outer end of a sleeve'or 'tube forming one of 'the parts of a holder or receiver for the multiple terminal Iplug. With this structure, the interior ofthe casing is positively sealed against vthe ingress of iluid under pressure, "through the lateral openings thereof.

"Ano'therobject is Vto provide in la hydropho'ne fs'trtic'tiie, means for retaining each lterminal lplug axially in pl: in the easing, said means including 'a peripheral hangt-,bn

the plug which is clamped between a contact holder memb'' "and 'the "slv' referred 'to above.

A further object is to provide a hydrophone structure in which the several parts of the plug retaining means are connected to and disconnected from an end of the main casing by means of a single nut-like element or ferrule screwed onto the threaded end of the casing, thus greatly facilitating 'assembly and disassembly `vof the Iiats.

AFurther objects of theinvention will appear from the following description and fr'o'rn the drawings, which a'r' for/ the 'purpose of illustration only, and in whoh:

Fig. l is a vertical cross-sectional view of the earth along a line of exploration, illustrating the use of the hydrophones'ior'm'ing the subjctfrnatt'er of tlii'sinvention;

Figs 2a and 2b respectively are longitudinal, part sectional views of the upper and lower portions of the improved hydrophone,

, Fig. 3 is a cross-sectional View, taken on line 3--3 `of FigfZb; Y

Fig. is 'an enlarged longitudinal cross-'stio'rla'l detail of the lower portion of the hydrophone',

LFig. `5 isa sectional View of one end of a 'cable section; and, l

Fig. 6 is an isometric View of the essie.

`Referring to the drawings in detail, ythe 4present irnfrom above `the surface of the ground byany suitable iriefrls', as the hoist' oi a inotor-trucli 7 The string ofhydropho'nes Ais suspended vvitliingan uncased receiver hole which is drilled into the earth to a predetermined depth. T he number of hydiophones may vary in accordance wiih the number of vertically spaced stations at which seismic waves are to be received, the vertical spaciilgof Athe hydrophones also being dependent upon the various conditions andthe recording equipment employed, but usually being about ten feet apart. L phones are identical in construction, aegserisa in daan.

Referring to lFigs. '2a and 2b, eachhydrophone 5 inc'ldes a main elongate tubular casingil which, as shown, consists` of several .parts Il, 12', 13 and :14, suitably joined in aiil alignment, .for example by welding. Secured in place at the upper end of Vthe casing section 11 and at the lower end of the casing section 1'4 arc upper and'lovver end lnrnbers 17 and 18. These members nd 18 are held in position by means oi annlila`r clamping nuts u19 scre ed onto the externally threaded eaasisf f 'the sentons, 'nach of the clamping nuts is provided `with an inwardly directed lflange vZ'lthat en- ,gagesv an efiternalflange Zllat the inner end of inem- Ber 517 o'r T8 see P igs12a, and 4), the nuts 19 having spaimr wrench holes 22. Each end member 17 and IS hvsvaii longateopening A24' in its Iside, 4for the purpose to ci lihed hereinafter.

The outer ends of the members 'I7 and IS are closed by internally threaded plugs '2'5 rinto which 'are screwed theA ends `26 of lengths 'or sections 27 of a 'rope-type' tr'atndsteel supporting cable,the ends' 2 6 being sqvii'gedwor otherwise secured to the ends ofthe cable sect1 ns 27. Lochnuts 27a lock the ends f6 of `the cable s ons irnily in place. 'As shown in Fig. 2a, uthe low 41". couphng end 216 of each cable section receives a sie 29 having sa integrin narrare er sat1 'su by when hahdl ng of 'the hydrophone is facilitated.` It is ft'o be only one will be nfa time construction he upper and Ilower lends of thefhydrophone 4is identical, except 'that opposite threads are lern- Wed at oppositfendis to facilitate connection oi cable fthreio. vFor this rea'son, a detailed descriion V ne end, for erainple the lower 'end shown in E igs. 3 andl, 'will nSiliiice --ifor aolear 'and full unclerstending offthe end struc ures. 'Referring tanifgntgefaengeaa jsfruetnfe'iaciuaes maaar- W" "'toih parts T8, 19, 1'9, 2'5 and Z6, "a fn'a e co'lt armata element or holder 40 of hat shape, the holder having a disc-like upper portion 41 and a depending skirt portion 42. The lower end of the portion 42 is reduced in diameter to provide an annular shoulder 43. skirt po-rtion is further provided with a circumferential 14 is a retainer ring 46 which engages the shoulder 43 of the holder 40 to force the latter inwardly and thus compresses an O-ring seal 47 between the bead 44 and the seat 45. Thus, the holder 40 is held in place within tends through the sive device 49 ible pressure-responsive diaphragm that is exposed to fluid in the receiver hole. Narrow slots 51a are milled into the side wall of the casing in communication with the upper end of the recess 51. The slots act as vents to prevent air from being trapped therein. responsive means in the tions in pressure of the fluid therein cause corresponding voltages to be generated by the piezo-electric crystals. These voltages are applied to the input of an amplifier unit A through Suitable wires (not shown). The pressure-responsive device 49 is described in more detail and claimed in copending patent application Serial No. 366,093. A removable plug 54 in the Wall of the lower Side of the lateral passage 48 facilitates removal and replacement of the pressure-responsive device 49. Compres'sible rings 59a and 5917, respectively, provide seals between the case 12 and the pressure-responsive device 49 and the plug 54.

The section 12 is provided with longitudinal passages 55 extending past the sides of the lateral passage 48. Electrical conductors, to be later described, extend through the longitudinal passages. The male contact holders 40 close the ends of the casing and, together with the pressure-responsive device 49 and the plug 54, define a divided chamber 52 in which the piezofelectric crystals 53 are disposed, the chamber being illed with dry nitrogen.

The transverse portion 41 of the contact holder 40 carries a plurality of glass insulators 56 into which extend In each hydrophone a pair of wires is connected to the output of the amplifier unit A and other wires may also terminate in the amplier unit; rbut the remaining wires that connect to amplifiers in lower hydrophones are led through the longitudinal passages '55 to appropriate points in the lower holder. In practice, the connections are cycled or rotated in order that the hydroface with the respective hydrophone positions as explained more `fully in copending patent application,` Serial No. 355,507.

A 'female contact or terminal member 60 has its upper end seated within the holder 40 and is provided with holes receiving the prongs 58. The terminal member 60, which is of the type commonly referred to in the electrical art as a Cannon plug, has an inner dielectric body and conductor means extending therethrough. The Cannon plug 60 is properly located and held against holder engaging in the plug. y Connected to the conductor means of the Cannon plug 60 .are the exposed ends of the wires of ,insulated conductors 64 of multi-conductor cable section 65 which are arranged in strength member In practice, the pairs of the cable section 65,

the disc having a plurality of mutually spaced wires 64 of the cable tight seal about each insulated conductor.

A sleeve 7'5 has its upper end disposed in the annular space between the terminal plug 60 and the bore of the end 19 of the casing part 14, this end of the sleeve having a peripheral lflange 76. A clamping ring 77 has a reduced upper end which is s'lidable in the annular space between the sleeve 75 and the end 19 of the part 14, the lower end of the ring being engaged vby the upper end of the tubular member 18. Interposed between the clamping ring 77 and the flange 76 of seal 78. The termina-l plug 60 1s provided with a peripheral bead 80 which is secured to means of a swaged bead, and is of the skirt 42 and the end 76 the plug trmly in place.

Screwed into the outer end of the sleeve 75 is a bushing 84 through which the cable section 65 extends. Interposed Abetween the bushing 8'4 and the head 68 is a compres-sing ring 85 having a tapered concavity conforming to the vcontour of the frusto-conical end 69 of the head to adapt it to receive the head. It is thus seen that when engaged 'between the end of the sleeve '75 to retain into `tirm engagement with the interior of the sleeve 75 so as to seal the latter, and that the head 68, which is integral with the cable section 75, seals the latter. sequently,

It is to be noted that it the outer sheath of a cable `becomes fractured, leakage of fluid into a hydrophone along the exterior surfaces of the conductors is prevented by the vulcanized head 68. It is also to be noted that if a defect should occur in the vulcanization, such leakage is also prevented by the `compression of the head 68 about the conductors 64 and against the disc 72.

With the end closure structures assembled at the upper and lower ends of the casings -10 of the several hydropagina are aina-assessed sable secties@ es einem v h phon that is, `from lthe lower "end of hydiphne to 'the upper Aend f the next lwer-liy ro- Byife''sbn 'of the Caution plug Connectors `60 and the conductors 57, the several wires 'of vthe cajble extend aewnw any rnu'gnthssev" i l @sans 'ontmetors ler the anni@ seing e n amplifying unit A therein. As will be apparent, afeertain t l i Aef are cable feesrpjrsafe'tenniata f-agir v prev `i1 'die'ated, the several hydropho 'supported 'within the freceiver f8 fsolelvjby the table-i8, ae" ction ef porting dale 27 itendiig lbetw' pair -of the-'hydrophones 4f the se es; "Elie'sections 65 of th i-ilti-c'ridiic cableJ Ien the ether hand, "extend 'loosely' between the hydrophones, lso that they i'erii'ain unstrthed and uhst ed. AS `'shown in Fi `1', l"a cable section 27 extends w'nw'ardly frorn 'the iwermsst hydmphsne ef 'fuesen-es aina carries-a weighted ik'r rr anchor 91 at its llower end, the anchor serving as a pilot "as the `string of hydrophones is lowered into ythe lreceiver fhle 8 where the hydrphone's are immersed 'in'vvll fluid'9.

The hydrophones of this invention lare 'particularly liseifwl vivljerefa high degree of accuracy is desired in the deterinitiation of th'e strike and dip of underlying lfori'nations n Ithe method described and claimed in the aforementioned copending patent application, 'andati-ius are particularly useful where the dips are 'small 'and where small differences in dips may rnea'n 'thejdier- 'ence between the presence or absence of mineral deposit at a particular position in the varea being surveyed. Vari bus 'changes which will now suggest themselves to those y skilled in vthe art may be made in the form, material, details v'of 'construction and arrangerncnt'of the various 'elements "of the linvention without departing from its main principles. It is ltherefore 'to be understood that the i'nvention includes not only the specific form ofjconstructio'n illustrated in the drawings and described in detail herein, but also includes all 'other embodiments 'thereof within the ls'c'op'e of the appended claims.

` The invention "claimed is:

1. fl'jn :seismic wave-detecting apparatus; a plurality of i ciat'ed Lwith said diaphragm; an electrical amplifier unit within `'each 'casing connected to the vpressuredesponsive fnean's therein; and a multi-conductor cable means hav- 'ing va partthe'reof coextensive with the hydrophones and extending thrtiugh the vcasings thereof with Yits individual cnduetors "electrically connected to said amplifier units. 2. In seismic wave-detecting apparatus: aplurality of drciphotlesA adapted to be "supported -in huid, each hyd phone including an elongate casing having a transversepas's'a'ge extending therethrough and communicating at either side with such huid, and a pressure-responsive ice arranged in the casing, vsaid pressure-responsive de vlc'e ceniprising'an external pressure-responsive diaphragm fotti'riing Va part 'of the vtransverse wall of said transverse if' 'aac' pressu responsive device also comprising a pressurevsensitive rneansfin'the casing operatively associated with said diaphragm; a plurality of ysnr'iporting cable sections "each connected b'efwe'en the lwer 'end of Aone of Lsaid Serial No. 319,969 i and being exposable to uid in said passage, said y sure-responsive device comprising v upper end extending into one 8 ele rical ainpliii'er unit within each casing connected 't' the pressurcre'sp ive means therein; and a tnu'lti-*crr d or cable rneans "cex'tensive with the hydropho'nes and tending through the casings "hereof with individual cnduetors electrically connected to said amplifier' units.

3. In seismic wave-detecting apparatus: a plurality of hydrophones adapted to be arranged in a bore hole filled with `huid, each hydrophone including an elongate casing hav-ing a transverse passage extending therethrough and communicating at either vside with iuid in which said casing is immersed, and having a longitudinal passage means therein extending past said transverse passage, and a pressure-responsive device arranged in the casing, said preslan external pressureresponsive diaphragm forming a part of the transverse wall of said transverse passage and being exposable to huid in said passage, said pressure-responsive device also comprising a pressure-sensitive means in the casing operatively associated with said diaphragm; a plurality 'of supporting cable sections each connected between vthe lower end of one of said casings and the upper end ot' the vnext flower casing", an electrical ampliicr unit within each casing connected to the pressure-responsive means therein; 'a multi-contact electrical connector plug within the upper and lower end of each casing; wires joined to the contacts of the upper connector plug of each hydrophone, certain of said wires being connected to theam'pli- 'er unit thereinfand the remaining wires extending through said Ilongitudinal. 'passage means and being joined to the contaets of the ylower connector plug of each said hydropho'n'e; and-'multifconductor'cable sections, each having an of saidcasings and a lower end extending into the next lower casing, the individual vc'ondu'c'tors of said multi-conductor cable sections being joined lto lthe contact'sof said connector plugs.

4. In 'seismic wave-detecting apparatus: wa plurality of hydrophones ladapted to be supported in fluid and -each having an elongate casing provided with lateral openings at its upper and lower ends; a plurality of supporting cable sections e'ach connected between the lower end of one of said casings andthe upper endoic the'next lower casing; a pressure-responsive device arranged in each hydrophone, each p es'sure-responsive device having an external pressure-responsive diaphragm forming a part fof the ywall of the corresponding casing and being expo'sable 'to 'uid in which "said each hydrophone is immersed and having 'a p'ressnresensitive means in lthe 'casing operatively associated with said diaphragm;l an electrical amplifier unit t chj'c'a'sing connected to vthe pressure-responsive nieaii therein; a multi-contactelectrical connector Lplug within the upper andlower ends 'of each 'casingpfwire's r 't'o the lower co'nnector'plug of said each hydrophone; and

mul'tiicndut'or Ucable sections "each having an upper end extendi g-fintoon'e ofsaid casing's through the low'enlatcral openingthereo'f and a 'lower end extending into the 'next lever'easing through the upper llateral opening thereof, the individual conductors of said multi-conductor cable sectio being-'joined to the contacts of the connector 'plugs adjacent'the ends thereof.

y5. v"In "seismic wave-detecting apparatus: a plurality ofhydrophones adapted to be supported in duid and eachV having an "elongate casing provided with lateral 'openings "'a't'it's upper and lower ends; a plurality of supporting'cablese'c'tions each connected between the lower 'end of a'said'casing and the upper end of thenext lower easing; `a pes'su'reirespo'nsv'e device arranged in each hydrophore, e h pressure-'responsive device having an `external :pressure-responsive diaphragm forming aspart ef the wallfofh'the corresponding Ucasing and being exposa-bie to uid'in lwhich :said `'earch hydropheue is irnmersed, and having a pressure-sensitive `means "in the "easing l'operat'ive1y associated "with 'fsaid diaphragm; "an

, tothecontaetsof :the upper connector plug of each electrical amplier unit within each casing connected to the pressure-responsive means therein; multi-contact electrical connector plugs within the upper and lower ends of each casing; wires joined to the contacts of the upper connector plug of each hydrophone; certain of said wires being connected to the ampliiier unit therein and the remaining wires being joined to the lower connector plug of said each hydrophone; multi-conductor cable sections each having an upper end extending into a said casing through the lower lateral opening thereof and a lower end extending into the next lower casing through the upper lateral opening thereof, the individual conductors of said multi-conductor cable sections being joined to the interior of said casings inwardly of their said openings.

6. In seismic wave-detecting apparatus: a plurality of hydrophones adapted to be supported in tluid and each having an elongate casing having detachable end portions each provided with a lateral opening; a plurality of supporting cable sections each connected between the lower end portion of one said [casing and the upper end portion of the next lower casing; a pressure-responsive device arranged in each hydrophone, each pressure-responsive device having an external pressure-responsive diaphragm forming a part of the wall of the corresponding casing and being exposable to iluid in which said each hydrophone is immersed and having a pressure-sensitive means in the casing operatively associated with said diaphragm; an electrical amplifier within each casing connected to the pressure-responsive means therein; a multicontact electrical connector plug within each detachable end portion; wires joined to the contacts of the upper connector plug of each hydrophone, certain of said wires being connected to the amplier unit therein and the remaining wires being joined to the lower connector plug of said each hydrophone; multi-conductor cable sections each having an upper end extending into one said casing through the lower lateral opening therein and a lower end extending into the next lower casing through the upper lateral opening therein, the individual conduccompressible sealing means within said end portions sealing the interior of said casings.

7. In seismic wave-detecting apparatus: a plurality of hydrophones adapted to be supported in fluid and each having an elongate casing having detachable end portions each provided with a lateral opening; a plurality of supporting cable sections each connected between the lower end portion of one said casing and the upper end portion of the next lower casing; a pressure-responsive device arranged within each hydrophone, each pressureresponsive device having an external pressure-responsive diaphragm forming a part of the wall of the corresponding casing and being exposable to fluid in which said each hydrophone is immersed and having a pressuresensitive means in the casing operatively associated with said diaphragm; an electrical amplifier within each casing connected to the pressure-responsive means therein; a hollow holder element having contact prongs within each detachable end portion; a multi-contact electrical connector plug within each detachable end portion and having contacts engaging said prongs; contacts of the upper connector plug of each hydrophone, certain of said wires being connected to the amplilier unit therein and the remaining wires being joined to the lower connector plug of said each hydrophone; multiconductor cable sections each having an upper end extending into a said casing through a said lateral opening and a lower end extending into the next lower casing through a said lateral opening, the individual conductors of said multi-conductor cable sections being joined to the contacts of said connector plugs, each of said end l()V portions comprising clamping means operative externallyl of the casing for clamping said plug in place in the casing and a sleeve disposed coaxially within the casing and connector plug; a first resilient sealing means.` integral with said multi-conductor cable and disposed within said sleeve, said first sealing means engaging the interior of said sleeve to effect a iluid-tight seal between the multiconductor cable and said sleeve; and a second sealing means engaging between said sleeve and the interior of said casing to eifect a fluid-tight seal therebetween.

8. In a hydrophone: an elongate casing having a transverse passage extending therethrough and communicating at either side with tluid in which said casing is immersed and having longitudinal passage means therein extending past said transverse passage, and a pressureresponsive device arranged in the casing, said pressureresponsive device comprising an external pressure-responsive diaphragm forming a part of the transverse wall of said transverse passage and being exposable to Huid in said passage, said pressure-responsive device also comprising a pressure-sensitive means in the casing operatively associated with said diaphragm; an amplifying unit Within the casing and electrically connected to the pressure-sensitive means; and a multi-conductor cable means extending through said casing, part of said multi-conductor cable passing through said longitudinal passage means, certain of the conductors of said cable terminating within said casing and being electrically connected to said amplifying unit.

9. In a hydrophone: an elongate casing having a transverse passage extending therethrough and communicating at either side with uid in which said casing is immersed and having longitudinal passage means therein extending past said transverse passage, and a pressureresponsive device arranged in the casing, said pressureresponsive device comprising an external pressure-responsive diaphragm forming a part of the transverse wall of said transverse passage and being exposable to iuid in said passage, said pressure-responsive device also comprising a pressure-sensitive means in the casing operatively associated with said diaphragm; an amplifying unit within the casing and electrically connected to the pressuresensitive means; a multi-contact connector plug at each end of the casing; and wires joined at the contact of the upper connector plug, certain of said wires being electrically connected to said amplifying unit, the remaining wires extending through said longitudinal passage means and being joined to the contacts of the lower connector plug.

10. In a hydrophone: an elongate casing having a transverse passage extending therethrough and communicating at either side with iluid in which said casing is immersed and having lateral openings at the ends thereof; a pressure-responsive device joined to the contact of the upper connector plug, certain of said Wires being electrically connected to said amplifying unit, the remaining wires being joined to the contacts of the lower connector plug; and resilient iluid-tight seal- "unit; Land resilient,

ing inlean's compressed Yby said clamping means for sealing the interior-'of said casing against theentrance of `iluid iherento.

l1. lnaihydrphone: a casing having a late-ral opening in side', a 'pressure-responsive device arranged yin said casing, 'said pressure-responsive device comprising an y'exteinl pressure-responsive `diaphragm forming a part of the csin'gw'all vand being eXposable to duid in which the hydrophone is immersed, said 'pressure-responsive device also vcomprising la pressure-sensitive means in the `casing operatively associated with said diaphragm; an amplifying `unit within the `casing and electrically -connected to 'thepre'ssure-sensitive means; a supporting cable connected 'axially to vthe upper end Vvof the casing; 4a 'multi-contact connector plug `within the casing; tive externally 'of lthe "casing 'for clamping said plug in place "in the Jcasi-ng; a multiconductor'cabl'e extending 'into 'said casing "through 'said 'lateral opening -with its individual lconductors joined to said connector plug, certain yof said conductors being 'electrically connected to said 'amplifying unit; and resilient, vfluid-tight sealing means compressed by said clamping means for sealing the interior 'of 'said casing 'against the entrance of iluid `thereinto.

12. AIn ahydrophone: a casinglhaving a lateral-opening in its side; a pressure-responsive device arranged in said casing, said pressure-responsive device comprising an externalpressure-responsive Vdiaphragm forming a part of the casing 'wallfand being expo'sable to duid in which the 'clamping means op'er-ahydrophone is immersed, said 'pressure-responsive 'device p also comprising a pressure-sensitive means in the casing "operatively associated with said diaphragm; `an amplifying unit within the casing and electrically connected to the pressurefs'ensiti've means', a supporting lcable 'connected iari'all'y tothe upper end of the casing; a multi-contact connector plug within the casing; clamping means 'opera- "tive externally of vthe casing for clamping said plug in .place in "the easing; 'a multi-conductor kcable 'extending into said 'casing through said lateral opening 'with its "individual conductors joined to said connector plug, `certain "of "said conductors being electrically connected -to said'arnpli'fying unit; and resilient, duid-tight sealing means compressed bysaid clamping-meanstfor sealing the vinterior of said casing against the entrance of lduid thereinto, one of 'said sealing means being integral with 'said multi-conductor "cable.

l5. ilin a hydrophone: a casing -having a lateral open- 'ing in its side; a pressure-responsive 'device 'arranged in said casing, said pressure-responsive device comprising an external 'pressure-responsive vdiaphragm forming a part of the casing wall and being exposable to the r hydrophonc is immersed, said pressure-responsive de- 'vice 'also comprising a `pressure-sensitive l*means Vin lthe casing operatively associated with said diaphragm; an amplifying unit within the 'casing 'and'electrically connected t'othe pressure-sensmve means; a supporting cable conr neet'ed Va'iiially to the upper Vend of "the casing; a -hollow holder v'element having contact prongs; a connector plug disposed 'within said holder elementand having contacts engaging said prongs; clamping'meansoperative'externally of the casing for clamping'said'plug in place in 'the'c'asing; :a multi-'conductor cablefextendinginto'saidtcasingthrough its said'opening with vits Vindividual conductors joined to the 'contacts of'sai'd connector plug, certain 'ofsaid conductors being electrically connected to :said amplifying by said clamping rneans'for *sealing the interior of said casing against the entrance ofilui'd thereinto,'one'o`f"said sealing means being vintegral with said multi-conductor cable.

Zing in its side; a `'piressure-'resp'o'nsive device arranged `in Zsa d c ng, said pressure-responsive 'device 2corripri'sing an "e ternal pressure-'responsive 'di-aphragn'i "forming fa f the casing'lwall landlbeingfexpos'a'ble ln'id 1in wir. h*mehydrophoneisnmnersed :said l"pressi'rre-responfluid in which t "duid-tight 'sealing means f compressed 1` In a hydrophone: a-casing having `al'ateral "openli.

sive device also comprising a pressure-sensitive means Ain the casing operatively lassociated with said diaphragm; 'an amplifying unit within 'the `casing and electrically connected to the pressure-sensitive means; a supporting cable connected axially to fthe upper end of the casing; a hollow holder element having lcontact prongs; a connector plug disposed within said holder element and having contacts engaging ysaid prongs; clamping means operative externally lof the lcasing for clamping said plug in place in the casing; a multi-conductor cable extending into said casing through said lateral opening with its individual conductors joined to the contacts Aoi? said connector plug, certain of said conductors being electrically connected to said vamplifying unit; a sleeve disposed coaxially within the casing and through which said multi-conductor cable extends to said connector plug; a rst resilient sealing means integral with said `multi-conductor cable and disposed within said sleeve, lsaid first sealing means engaging the interior of lsaid sleeve to eifect a iluid-tightseal between the multi-conductor vcable and said sleeve; and a second `sealing means engaging rvbetween said sleeve and the interior of said casing toetect a fluid-tight seal therebetween.

15. "In a hydrophone: a casing having a lateral opening in its side; a pressure-responsive device arranged Tin -said casing, said pressure-responsive device 4comprising 'an 'external pressure-responsive diaphragm forming a part yof the 'casing Vvvall .and being exposable to fluid vin which the hydrophone is immersed, said pressure-"responsive de- 'vice also comprising a pressure-sensitive means in Ithe casing operatively associated lwith said diaphragm; an amplifying v'unit within the casing and electrically connected vto the pressure-'sensitive means; a 'supporting :cable connected axially to lthe uppcr end of `the casing; a hollow holderelement 'seated within 'the casing `coaiially thereof, said element having lcontact prongs; a connect0r plug disposed Within saidh'oider element Aand having contacts vengaging `said prongs, said plug having `a peripheral bead; a sleeve disposed `coaxially Within the casing and having an inner end engaging said bead `of said plug; a multi-conductor'cableeextending into 'said'casing through its Ysaid opening' with its lindividual conductors `joined to the-contacts of 'said connector plug, certain of said 'con- `'ductors being electrically `connected 'to said amplifying unit; a lfirst resilient sealing means integral withs'aid multiconductor cable and disposed Within the 'outer end of said sleeve; a 'second resilient seaiing means disposed between said :inner end of said sleeve andsaideasing; `a 'first clamping `means at'the outer end of -sai'd sleeve for compressingsaidfirst sealing means laterally 'againstthe interior of :said `sleeve so as to prevent lluid leakage 'throughthe llatter; and'alsecond clamping means operative to vretain -said holder 'element "seated within "Said casing, to 4cause the 'inner Ven'd lof said sleeve 'to 'engage lirmly against said bead of said 'fplug so `as'to vclamp Athe 'plug in'place 'against 'said holder 4element, and -"to corn- 'presssaid 'second sealing Ymeans between said 'sleeve .and saidcasing so as to prevent vfluid'leakagetherebetween.

16. ln 'a'hydrophonez a'casinghavinga lateral opening in `its side; a pressure-responsive device arranged in said casing, "saidpressure-responsive device comprising an external pressure-responsive diaphragm Lforming a part 'o'f the"casing'wall andzbeing expo'sable 'tot'flnidin which said hydrophoneiis immersed, said pressure-responsive 'device also vvComprising a 'pressure-sensitive means inthe casing operatively associated with 'said diaphragm; anfamplifying unit'within the casing and electrically connecte'dito lthe pressure-sensitive means; a supporting cable connected axially to `the upper 'end of the casing; afhollow holder element seated'within the casing coaxially "thereof,;sai`d =element having cor'rtact prongs; 'a `connector plug ldisposed Within said :holder element and n:having contacts Vengaging said-prongs, v'said plug having Aa peripheral '-bead; "a V"sleeve end engaging rvsaid fbea'd, said fend 13 flange; a multi-conductor cable extending into said casing through said lateral opening with its individual conductors joined to the contacts of said connector plug, certain of retain said holder element seated within said casing, to cause the inner end of said sleeve to engage firmly against said bead of said plug so as to clamp the plug in place against said holder element ,and to compress said second sealing means between said sleeve and said casing so as to prevent iiuid leakage therebetween.

17. In a hydrophone: a casing having an opening in its side; a pressure-responsive device arranged in said casing, said pressure-responsive device comprising an external pressure-responsive diaphragm forming a part of the casing wall and being exposable to fluid in which the hydrophone is immersed, said pressure-responsive device said opening with its individual conductors joined to the contacts of said connector plug, certain of said conductors being electrically connected to said amplifying unit; a first resilient sealing means integral with said multi-conductor cable and disposed within the outer end of said sleeve; a second resilient sealing means disposed between said inner end of said sleeve and said casing; a first clamp- 18. In a hydrophone: a casing having an opening in its side; a pressure-responsive device arranged in said casing, said pressure-responsive device comprising an external pressure-responsive diaphragm forming a part of the pressure-sensitive means; axially to the upper end of the casing; a hollow holder element seated within the casing coaxially thereof, said element having contact prongs; a connector plug disposed within said holder element and having contacts engaging 14 said prongs, said plug having a peripheral bead; a sleeve disposed connector plug, certain of said conductors being electrically connected to said arnplifyi g unit; a first resilient sealingmeans integral with said multi-conductor cable and disposed within the outer end of said sleeve; a second resilient sealing means disposed between said inner end of said sleeve and said casing; a first clamping means at the outer end of said sleeve for compressing said first sealing means laterally against the interior of said sleeve so as to prevent fiuid leakage through the latter; and a second clamping means operative to retain said holder element seated within said casing, to cause the inner end leakage therebetween, said second clamping means including a tubular end member surrounding said sleeve and having an annular external flange at its inner end, a clamping nut screwed member and said flange of said sleeve and engaging said second sealing means.

19, In a hydrophone: a casing having an opening in its side; a pressure-responsive device arranged in said casing, said pressure-responsive device comprising an eX- ternal pressure-responsive diaphragm forming a part of the casing wall and being exposable to uid in which the hydrophone is immersed, said pressure-responsive denected to said pressure-sensitive means; a supporting cable connected axially to the upper end of the casing; a hollow holder element seated within the casing coaxially thereof, said element having contact prongs; a connector plug disposed within said holder element and having contacts an annular external fange within said casing; a multiconductor cable extending `into said siug through its said opening with its individual conductors joined to the contacts of said connector plug, certain of said conductors being electrically connected 1.5 and having van internal flange at its outer end engaging said flange of said end member, and a compressing ring surrounding said sleeve between said iiange of said end member and said flange of said sleeve and engaging said second sealing means.

20. In a hydrophone comprising: a casing having an opening in its side; a pressure-responsive device arranged in said casing, said `pressure-responsive device `comprising an external pressure-responsive diaphragm forming a part of the casing wall and lbeng exposable to fluid in which the hydrophone fis immersed, said pressure-responsive device also comprising a `pressure-sensitive means in the casing operatively associated with said diaphragm; an amplifying unit within the lcasing :and electrically connected to 'said pressure-sensitive means; a supporting cable connected laxially to the upper end of the casing; a hollow holder element seated within the casing coaxially thereof, said element having contact prongs; a connector plug disposed within said holder element and having .contacts engaging said prongs, said plug having va peripheral bead; a sleeve disposed eoaxially within the casing and having an inner end engaging `said bead of said plug and having an annular vexternal flange within said casing; a multi-conductor cable extending into said casing through its said opening with its 4individual conductors joined to `the contacts of said connector plug, certain lof said conductors being electrically connected lto said amplifying unit; a first resilient sealing means integral with said multi-'conductor cable and disposed within the outer end of said sleeve; a second resilient sealing rmeans disposed between said inner end of said sleeve and said casing; a first clamping means .at the outer end of said sleeve for compressing vsaid first :sealing means laterally against the interior of :saidsleeve so as kto prevent fluid leakage through the latter; :a second clamping means operative to retain said 4holder element seated within said casing, to cause the Ainner end Aof said sleeve to engage firmly against said bead of said plug so vas lto `clamp the plug inl place againstsaidholder element, and to compress saidsecond sealing means ybetween said sleeve and said casing so as to prevent iiuid leakage therebetween, said first sealing means 'having va virusto-conical o uter end, and said first clamping means including a ring surrounding said multi-conductor cable `and z slidable within said sleeve, said ring having frusta-conical end, `and a ,bushing screwed into the outer end of said sleeve Vand engaging said ring, Said second clamping means including a tubular vend member surrounding isaid sleeve and having van annular vexternal flange at its inner end, a clamping nut srewed onto the end of the :casing and having an internal vange at its outer end engaging said iiange of said `end :member anda compressing ringrsurrounding said sleeve between said :ange of said y'end tmernber and saidgflange of said sleeve and engaging lsaid second sealing means; and a third resilient sealing means compressed between said holder elementand the interior of said casing.

21. In a hydrophone comprising: a casing having .an opening in its side; a pressure-responsive .device arranged in said casing, said pressure-responsive device comprising an external pressure-respo sive diaphragm forming .a part of the casing walland being *.exposable to uid in which .the hydrophone is immersed, said pressure-respon- `a tapered interior receiving said sive device also comprising a pressure-sensitive means in the casing operatively associated with said diaphragm; an amplifying unit within the casing and electrically connected to said pressure-sensitive means; a supporting cable connected axially vto the upper end of the casing', a hollow holder element seated within the casing coaxially thereof, said element having contact prongs; a connector plug disposed within said holder element and having contacts engaging said prongs, said plug having a peripheral bead; a sleeve disposed coaxially within the casing and having an inner end engaging said bead of said plug and having an annular external flange within said casing; a multi-conductor cable extending into said casing through its said opening with its individual conductors joined to the contacts of said connector plug, certain of said conductors being electrically connected to said amplifying unit; a first resilient sealing means integral with said multi-conductor vcable and disposed within the outer end of said sleeve; a second resilient sealing means disposed between said inner end of said sleeve and said casing; a :rst clamping -means at the outer end of said sleeve-for compressing said irst sealing means -laterally against the interior of said sleeve so as to prevent uid leakage through the latter; a second clamping means operative to retain said holder element seated within said casing, to cause the :inner ,end of said sleeve to engage firmly against said bead of said plug so as to clamp .the plugin place against said holder element, and to compress said second sealing means between said sleeve and said casing so as to vprevent iuid leakage therebetween, said iirst sealing means having a frusto-conical outer end, and s aid iirst clamping means including a ring surrounding said :multi-conductor cable and sldable within said sleeve, -said ring having a tapered 4interior receiving said frustoconical end, and a bushing screwed into the outer end kof said sleeve and engaging said ring, said second clamping means including a tubular end member surroundingsaid sleeve and having an annular external iiange at its inner end, :aclamping nut screwed onto the end of the Casing andhaving an internal `ange at its outeriend engaging said flange vof said end member and a compressing .ring surrounding Asaid sleeve between said flange of said end'membergand saidjiiange of said sleeve and engaging said second vsealing means; and a third resilient sealingmeans compressed betweensaid holder element vand the interior of ,said casing, said supporting cable having a threaded end screwed into .a threaded axial hole in said end member.

References Cited inthe tileof this patent UNITED STATES PATENTS 

1. IN SEISMIC WAVE-DETECTING APPARATUS: A PLURALITY OF HYDROPHONES ADAPTED TO BE ARRANGED IN FLUID, EACH HAVING AN ELONGATED CASING; A PLURALITY OF SUPPORTING CABLE SECTIONS EACH CONNECTED BETWEEN THE LOWER END OF ONE OF SAID CASINGS AND THE UPPER END OF THE NEXT LOWER CASING; A PRESSURE-RESPONSIVE DEVICE ARRANGED IN EACH HYDROPHONE, EACH PRESSURE-RESPONSIVE DEVICE HAVING AN EXTERNAL PRESSURE-RESPONSIVE DIAPHRAGM FORMING A PART OF THE WALL OF THE CORRESPONDING CASING AND BEING EXPOSABLE TO FLUID IN WHICH SAID EACH HYDROPHONE IS IMMERSED AND HAVING A PRESSURE-SENSITIVE MEANS IN THE CASING OPERATIVELY ASSOCIATED WITH SAID DIAPHRAGM; AN ELECTRICAL AMPLIFIER UNIT WITHIN EACH CASING CONNECTED TO THE PRESSURE-RESPONSIVE MEANS THEREIN; AND A MULTI-CONDUCTOR CABLE MEANS HAVING A PART THEREOF COEXTENSIVE WITH THE HYDROPHONES AND EXTENDING THROUGH THE CASINGS THEREOF WITH ITS INDIVIDUAL CONDUCTORS ELECTRICALLY CONNECTED TO SAID AMPLIFIER UNITS. 